That's a pretty good price. I've booked a car w/ Budget for Jan. @~$27/day. Where did you get your codes? I booked thru USAA's website. I have heard that prices sometimes come down closer to the time of your trip, so I keep checking to see. It can't hurt, since you can cancel your existing ressie right up to before your trip.
I agree with the PP. Book it now and check back every so often. Check with various companies too. Also, according to my father, he suggests clearing the cookies off the computer before checking. He swears you get cheaper rates when you do that.